Question

I have this code to change system time.

This code works but somehow doesn’t accept local system Time Zone.

It seems that I have to add some more methods to do it or ??

How it could be???

Any clue?

public static class SystemFunctions
    {
        public struct SystemTime
        {
            public ushort Year;
            public ushort Month;
            public ushort DayOfWeek;
            public ushort Day;
            public ushort Hour;
            public ushort Minute;
            public ushort Second;
            public ushort Millisecond;
        };

        [DllImport("kernel32.dll", EntryPoint = "GetSystemTime", SetLastError = true)]
        public extern static void Win32GetSystemTime(ref SystemTime sysTime);

        [DllImport("kernel32.dll", EntryPoint = "SetSystemTime", SetLastError = true)]
        [return: System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.Bool)]
        public extern static bool Win32SetSystemTime(ref SystemTime sysTime);

        public static bool SetSystemTime(DateTime dateTime)
        {
            SystemTime updatedTime = new SystemTime();
            updatedTime.Year = (ushort)dateTime.Year;
            updatedTime.Month = (ushort)dateTime.Month;
            updatedTime.Day = (ushort)dateTime.Day;
            // UTC time; it will be modified according to the regional settings of the target computer so the actual hour might differ
            updatedTime.Hour = (ushort)dateTime.Hour;
            updatedTime.Minute = (ushort)dateTime.Minute;
            updatedTime.Second = (ushort)dateTime.Second;
            // Call the unmanaged function that sets the new date and time instantly
            return Win32SetSystemTime(ref updatedTime);
        }
    }

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UPDATES

So the final solution was to convert local time to ToUniversalTime and just apply it.
But before we have to apply correct time zone as well.

Answer 1

SetSystemTime accepts only UTC time. So you need to do conversion from local to UTC in your C# code if needed.

Sets the current system time and date. The system time is expressed in Coordinated Universal Time (UTC).